This invention generally relates to control and diagnostic systems for internal combustion engines, and more particularly to engines having a powertrain control module and a motorized module, such as an electronic throttle.
In a modern automobile or truck with an internal combustion engine, there is typically a powertrain control module (PCM) which governs almost all important operating and safety features related to the vehicle powertrain. Certain functions of the PCM are more important than others, such as controlling an engine""s fuel, air and ignition. Therefore, the PCM incorporates a number of diagnostic elements and procedures for insuring proper functioning of the engine. These tools include self-diagnostic routines and procedures.
The diagnostic routines and procedures should be as automatic as possible and should be minimally-intrusive. That is, if the PCM routinely performs self-diagnostic procedures on a fuel system or air system, the procedures should not intrude on driver-commanded engine performance, and certainly should not intrude on vehicle operation. For instance, it may be desirable for the PCM to exercise a throttle valve in order to check actual position against intended position in the throttle body, or it may be desirable to measure throttle motor torque or current to determine whether the throttle control valve is stuck or is operating properly. Tests for these characteristics should not be run while the vehicle using these systems is operating, since performing the test may be inconsistent with operating the vehicle in the manner the driver requires. That is, operating the test while the vehicle is running could interfere with the operation or safety of the vehicle.
What is needed is a way to perform engine diagnostics, and in particular throttle diagnostics, while the vehicle or engine is not in operation. What is needed is a way to run engine and throttle diagnostics while the vehicle or engine is off-line.
One aspect of the invention is an engine diagnostic system. The engine diagnostic system comprises a powertrain control module and an electronic throttle operably connected with the powertrain control module. The system also comprises at least one sensor for indicating a parameter of the electronic throttle and an output for indicating a result, wherein the powertrain control module performs at least one test of at least one parameter of the electronic throttle when the electronic throttle is off-line. Another aspect of the invention is a method of diagnosing an electronic throttle connected to a powertrain control module of an internal combustion engine. The method comprises waiting for a period of time when the electronic throttle is off-line, and then testing the electronic throttle for at least one parameter of performance of the electronic module. The method also includes outputting at least one result of the test.
Another aspect of the invention is an off-line vehicle diagnostic system. The system comprises an electronic throttle of the vehicle, and a powertrain control module operably connected with the electronic throttle. There is at least one sensor for indicating a parameter of the electronic throttle, wherein the powertrain control module performs at least one test of at least one parameter of the electronic throttle when the electronic throttle is off line, and outputs a result of the at least one test.